Primary non-refluxing megaureters.
Megaureters may be primary or secondary, and the dilatation may be due to obstruction or reflux, or both or neither. The cause of primary obstructed megaureter is the aperistaltic and narrowed pre-vesical portion of the ureter. The inner sheath of the terminal ureter generally shows a reduced amount of longitudinal smooth muscle bundles and an increased amount of collagen. Primary non-refluxing megaureters represent 23% of all prenatal diagnoses of hydronephrosis. They are more common in males and on the left side, and in 25% are bilateral. In older children they may become symptomatic. The diagnostic work up should include an ultrasound, a micturating cystourethrogram and an isotopic renogram. Most primary megaureters regress spontaneously or remain stable without compromising renal function, but 10-25% require surgery because of a progressive reduction in renal function or increasing dilatation, or because they become symptomatic. The basic principles of surgical repair include: resection of the obstructing segment, reduction in size of the dilated ureter, and re-implantation into the bladder using an anti-reflux technique.
Merlini
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Department of Paediatric Surgery, Ospedale Maggiore della Carità Hospital, Corso Mazzini 18, 28100 Novara, Italy. emilio.merlini@maggioreosp.novara.it
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